Crimp, leading, and group size/location

Hey all, 

Background 
I was shooting my club match this past week and became quite frustrated. We shoot 4 nmc, 2 RF and 2 CF. I had a 281 and 277 with the RF and a 250 on my first CF. All typical for me. But in the second 45 nmc my group opened up by about 4 inches and was 5" low and to the left. I was dumbfounded. I scored a 281 and a 161 on the same card. FYI, rounds were zero 200 gr lswc 3.9 be. Gun has a kart gunsmith fit barrel.  

When I examined the barrel I notice it was leading. Not something that has ever happened to me before. I just set up a new press and figured something had to be wrong. Well, I messed up the crimp. It backed out and was set at .472 instead of my normal .468. In my head I feel as though that had to be the problem. It makes sense that the loose crimp would create some leading, but does it make sense that the group would open up, and poi change? 

Thank you for your time.

Yes crimp will change things dramatically. 0.472 is loose and you get not enough pressure built up and it goes to hell in a hand bag